The invention relates to the technical field of lifting and handling appliances for plasterboards in order to place them on walls and ceilings.
For many years, the Applicant has developed appliances of this type which are marketed under the brand name LEVPANO and which are the subject of numerous patents (EP 1640531, FR 2758150, FR 2780428). The Applicant is therefore one of the leading European companies which manufacture and market such appliances. Currently commercially available plasterboards have a standard width of 1200 mm. Nevertheless, there are signs of changes because plasterboards are becoming increasingly thicker and, consequently, more and more heavy. Moreover, in an attempt to ensure ease of handling, plasterboard manufacturers have been led to reduce the width of boards to 900 mm in the case of certain models and 600 mm for others, especially the 13 mm thick plasterboards which are most commonly fitted. There are therefore plasterboards of different widths: 600, 900 and 1200 mm.
In order to be able to fit plasterboards having these various widths, the Applicant has been led to revise the design of the board support in order to adapt to this new market situation. Because there was previously only one single plasterboard width, board supports were designed with fixed limit stop means at the end of the arms of the board support. Various solutions have been envisaged for solving the problem of making the board support easily adaptable to the dimensions of the plasterboards.
Initial research was therefore carried out to adapt the dimensions of the board support to those of the actual boards in accordance with functional needs. In practice, implementing the board support with telescopic components proved difficult to achieve and was relatively impractical to manipulate.
Other research involved providing the possibility of moving and fixing the position of limit stop elements by a seating and gripping effect with the plasterboard in question resting on these limit stop elements. In practice, such an implementation also proved to be relatively impractical, involving random positional adjustments and variable pressure forces and fixing which caused deterioration of the actual board holder.
The Applicant's approach was therefore to take a different direction by trying to design a means of quickly positioning the board limit stops safely, taking into account the lifting forces and handling of heavy loads involved. The Applicant also considered other possible changes in the dimensions of plasterboards over time involving dimensions other than the three dimensions currently adopted as stated above.
Also, according to the prior art, the limit stops arranged on the board support arm were capable of retracting in order to enable the board to press against the ceiling during installation, but the realisation of this implementation remained very hit and miss. Tackling this situation was therefore another of the Applicant's objectives.
The solution devised by the Applicant achieves all these objectives by being simple and safe and allowing easy, quick adjustment of the position of the limit stops depending on the dimensional constraints of the plasterboards. The Applicant's solution therefore satisfactorily copes with the constraints and stresses that are inherent in operating lifting and handling appliances which require phases during which boards are slanted and swivelled so that they are horizontal or vertical.